In recent years, as countermeasures against the air pollution and the global warming, a variety of countermeasures for a reduction of the CO2 emission amount have been taken. In particular, in the automobile industry, a reduction of the CO2 emission amount by introduction of an electric vehicle and a hybrid electric vehicle has been expected. As a power supply for driving a motor of each of these vehicles, development of a high-performance secondary battery has been advanced. In particular, the secondary battery as described above is required to have a high capacity and to be excellent in cycle characteristics, and accordingly, a lithium ion secondary battery having high theoretical energy has attracted attention among a variety of such secondary batteries.
In order to increase an energy density in the lithium ion secondary battery as described above, it is necessary to increase an amount of electricity stored per unit mass of each of a positive electrode and a negative electrode. Then, in order to satisfy such a requirement, it is extremely important to select an active material of each of the electrodes. Among such active materials, a variety of materials are used as a material that composes the negative electrode active material. For example, in Japanese Unexamined Patent Application Publication No. 2007-194204, it is disclosed to use crystalline metal, which is represented by silicon (Si), as a type of the negative electrode active material.